Communications: radio wave antennas – Antennas – Active antenna as reflector
Reexamination Certificate
1999-12-06
2001-07-03
Ho, Tan (Department: 2821)
Communications: radio wave antennas
Antennas
Active antenna as reflector
C343S7810CA, C343S840000
Reexamination Certificate
active
06255997
ABSTRACT:
PRIORITY CLAIM
This application is based on and claims the priority under 35 U.S.C. §119 of German Patent Application 199 45 062.5, filed on Sep. 20, 1999 the entire disclosure of which is incorporated herein by reference.
FIELD OF THE INVENTION
The invention relates to an antenna reflector for electromagnetic waves. The antenna reflector has a configured surface for reflecting beams emanating from spatially separated focuses or rather radiators positioned in these focuses for illuminating identical or common regions. The invention also relates to a system with such antennas. The radiators may be transmitters or receivers.
BACKGROUND INFORMATION
Reflectors having a configured surface configuration are known in the art. For example, European Patent Publication EP 0,920,076 discloses an antenna system with a reflector having a configured surface, whereby two beams or two bundles of rays emanating from two separate radiators are focused onto two different regions.
European Patent Publication EP 0,915,529 discloses a possibility for forming a single beam which is directed onto a region to be illuminated and which is formed with the aid of a reflector having a configured surface for collecting several beams emanating from several radiators which are connected together through a suitable distribution network.
U.S. Pat. No. 4,298,877 describes a reflector having a configured surface for focusing two beams onto two different receivers or rather receiver antennas of a satellite.
U.S. Pat. No. 5,684,494 discloses the focusing of separate beams having different polarities by means of a reflector arrangement comprising two reflectors. Each of the reflectors is constructed as a grid reflector so that it is effective only for one of the polarizations.
Conventional reflectors are of limited use for applications in which a bi-directional beam transmission (transmitting and receiving) is required with an effective decoupling of the transmitting direction from the receiving direction toward and from a single common region to be illuminated. The usefulness of conventional reflectors for the just mentioned purposes is rather limited especially if it shall be possible to use the same frequency and/or the same polarizations for the transmitting direction and the receiving direction. Thus, conventional reflectors have been subject to the following problems. In the case of a simple construction of the system using a single radiator for transmission and reception, there is an insufficient decoupling between the transmission direction and the reception direction of the electromagnetic radiation. Such decoupling must be achieved by additional structural components in the system such as diplexer circuits for separate transmission and receiving frequencies as is customary in conventional communication technology. When the transmission and reception frequency are the same, circulators must be used as is customary in radar technology. Producing or processing the electromagnetic radiation by these additional circuit components is costly.
In those conventional systems in which a decoupling of transmission and reception frequencies is to be accomplished, several radiators are required also resulting in costly structures as is the case for example in U.S. Pat. No. 5,684,494. However, the use of separate reflectors limits the number of useable polarization directions because different polarization directions must be provided for the transmission direction and for the reception direction. Thus, the data volume that can be transmitted through conventional systems is markedly limited.
OBJECTS OF THE INVENTION
In view of the forgoing it is the aim of the invention to achieve the following objects singly or in combination:
to provide an antenna reflector and system that makes possible a decoupled bidirectional transmission of electromagnetic waves while simultaneously achieving a maximal or at least an optimal data volume transmission;
to configure the reflecting surface of an antenna reflector in such a way that the reflector is capable of transmitting beams from separate radiators onto a common region, for example on the earth's surface;
to provide an antenna system with such a reflector for the bidirectional transmission of electromagnetic waves with a single reflector; and
to provide a method for ascertaining the antenna reflector surface configurations.
SUMMARY OF THE INVENTION
According to the invention there is provided a reflector for electromagnetic waves, said reflector comprising a reflector body having a configured reflector surface, said configured reflector surface comprising a plurality of localized surface areas, said reflector further comprising at least one group of spatilly separated focises, each of said localized surface areas having a surface topography with bumps and dents adapted for cooperation with said at least one group of spatially separated focuses for directing electromagnetix beams emanating from said respective group of spatially separated focuses onto a region to be illuminated by said electromagnetic beams or for receiving electromagentic beams emanating from a respective region, and wherein said bumps and dents of said localized surface areas have progressively smaller dimensions starting from a given first dimension of the bumps and dents of a first localized surface area of said configured reflector surface.
The present reflector is used in an antenna system according to the invention wherein the antenna system comprises at least one group of radiators with a first radiator and a second radiator forming said at least one group, whereby the first radiators are spatially separated from the reflector body proper, and wherein the first and the second radiator are arranged in respective focuses of the reflector so that first radiation beams emanating from the first radiator and second radiation beams emanating from the second radiator are directed onto a common region to be illuminated, for example on a surface region of the earth.
A method for determaining a surface configuration for a reflector for electromagnetic waves, said method comprising the following steps:
(a) stimulating a base reflector surface configuration of said reflector,
(b) defining spatial separated positions of radiators relative to said base reflector surface configuration in such a way that each radiator illuminates at least one localized reflector surface area of said reflector surface configuration,
(c) determining a reflectoion efefct of said refector surface configuration relative to electromagnetic beams emanating from radiators located inn said spatially separated positions defined in step (b),
(d) varying a topography in the form of bumps and dents of said at least one localized reflector surface area by making said bumps and dents progressively smaller than any bumps and dents of a preceding topography so that electromagnetic beams emanating from said radiators are directed onto a common region to be illuminated, and
(e) repeating steps (c) and (d) with progressively smaller dimensions of said bumps and dents until a defined directional effect of said electromagnetic beams onto said common region to be illuminated is achieved.
In this context the term “beam” or “beams” refers to a bundle or bundles of rays, respectively. The term “region to be illuminated” means a surface where beams reflected by the present reflector are received.
In another embodiment a reflector according to the invention comprises several groups of focuses, whereby beams emanating from one group of focuses are directed by the reflector onto a common or identical region to be illuminated. The beams from one group or from another group may be focused onto a common point to be illuminated, for example a remote receiver antenna in the region to be illuminated. Moreover, it is possible that the beams from several groups of focuses have a certain overlapping expansion in the region to be illuminated. This overlapping expansion can be adapted to the shape of the region to be illuminated, for example a portion of the earth's surfa
Hunscher Christian
Ratkorn Norbert
Sekora Robert
Truemper Michael
Daimler-Chrysler AG
Fasse W. F.
Fasse W. G.
Ho Tan
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